The invention relates to a vacuum valve, comprising a valve body with a first valve opening which has a first axis and is surrounded by a first valve seat, and with a second valve opening which has a second axis and is surrounded by a second valve seat, a first and a second closure element which are attached to a valve rod, a transmission piece which is attached to the valve rod and which is adjustable in a longitudinal adjustment direction from an open position, in which the first and the second closure element open up the first and second valve opening, into an intermediate position, in which the first and the second closure element overlap the first and second valve opening, but are raised from the first and second valve seat, and which is adjustable in a transverse adjustment direction from the intermediate position into a first closing position, in which the first closure element lies against the first valve seat, and counter to the transverse adjustment direction from the intermediate position into a second closing position, in which the second closure element lies against the second valve seat, a longitudinal stroke drive by which the transmission piece is adjustable from the open position into the intermediate position, a longitudinal stroke linear guide which has a longitudinal stroke guide part extending parallel to the longitudinal adjustment direction and a longitudinal stroke carriage which is guided displaceably by the longitudinal stroke guide part, where, for the adjustment of the transmission piece from the open position into the intermediate position, the longitudinal stroke carriage is displaceable linearly in relation to the longitudinal stroke guide part, or the longitudinal stroke guide part is displaceable linearly in relation to the longitudinal stroke carriage, in the longitudinal adjustment direction by the longitudinal stroke drive, and a transverse stroke drive by which the transmission piece is adjustable from the intermediate position into the first closing position or into the second closing position.
Vacuum valves in which, in order to close the vacuum valve, the closure element is first of all displaced in a longitudinal adjustment direction, which lies parallel to the longitudinal axis of the valve rod, from a first position, in which the closure element opens up the valve opening, into a second position, in which the closure element overlaps the valve opening, but is still raised from the valve seat, and, as a result, is adjusted in a transverse adjustment direction lying at an angle to the longitudinal adjustment direction into a third position, in which the closure element is placed against the valve seat, are also referred to as L valves.
In the case of a non-generic design of L valves, the valve rod is mounted pivotably about an axis lying at right angles to the longitudinal adjustment direction, in order to permit the adjustment of the closure element from its second position into its third position and back. In order to pivot the valve rod about the axis, use can be made here of slotted guide mechanisms, as known, for example, from U.S. Pat. No. 6,237,892 B1, U.S. Pat. No. 7,066,443 B2 or US 2012/0258242 A1.
In the case of L valves in which, in order to adjust the closure element between the second position and the third position, a parallel displacement of the closure element in a transverse adjustment direction lying at an angle, in particular at right angles, to the longitudinal adjustment direction takes place, according to a customary embodiment drive elements for adjusting the closure element between the second position and the third position are arranged on a supporting unit bearing the closure element, wherein the supporting unit is located within the valve housing of the vacuum valve and is attached to a valve rod led out of the vacuum region of the vacuum valve. Such embodiments of L valves are found, for example, in U.S. Pat. No. 6,056,266 A, U.S. Pat. No. 6,899,316 B2 and U.S. Pat. No. 7,611,122 B2. In this connection, U.S. Pat. No. 6,056,266 A and U.S. Pat. No. 7,611,122 B2 also reveal sequence controls in order to ensure the correct sequence of actuation of the piston-cylinder units. A further such sequence control for an L valve is found in U.S. Pat. No. 8,177,190 B2.
L valves in which a linear displacement of the closure element between the second position and the third position takes place, wherein both the drive for the adjustment of the closure element between the first and the second position and the drive for the adjustment of the closure element between the second and third position are arranged outside the vacuum, are found in WO 2010/034046 A1 and U.S. Pat. No. 7,762,527 B2.
Also in the case of the vacuum valve known from US 2013/0112906 A1, a linear displacement of the closure element between the second position and the third position takes place. The longitudinal stroke and the transverse stroke take place here by the use of a common drive arranged outside the vacuum region of the vacuum valve. The movement guidance of the closure element is brought about by slotted guide mechanisms which have control cams which engage in cam recesses.
A vacuum valve of the type mentioned at the beginning is found in U.S. Pat. No. 8,960,641 B1. The valve rod is guided displaceably in a longitudinal adjustment direction, wherein portions of a transmission piece which is attached to the valve rod form first and second longitudinal stroke carriages which are guided displaceably along rod-shaped guide parts. The longitudinal stroke carriages and the rod-shaped guide parts together form first and second longitudinal stroke linear guides. The rod-shaped guide parts are displaceable parallel to a transverse adjustment direction lying at right angles to the longitudinal adjustment direction and can be displaced in and counter to the transverse adjustment direction by a transverse stroke drive formed by pneumatic piston-cylinder units. In order to displace the valve rod in the longitudinal adjustment direction, use is likewise made of pneumatic piston-cylinder units, the valve rods of which are connected to the transmission piece, wherein this connection permits movability of the transmission piece in relation to the valve rods in the transverse adjustment direction. First and second closure elements are attached to the valve rod and can be used to alternatively close first and second valve openings by displacement of the transmission piece in and counter to the transverse adjustment direction. A disadvantage of the device found in this document is the relatively complicated design of the unit having the drive and guide elements, which leads to the vacuum valve being more expensive.
Further vacuum valves which have a valve housing with first and second valve openings which are alternatively closeable by first and second closure members are known from U.S. Pat. No. 6,390,448 B1, U.S. Pat. No. 6,913,243 B1 and US 2011/0095218 A1. Starting from the position in which the first and second closure elements are arranged centrally between the valve openings, closure either of the first valve opening by means of the first valve plate or of the second valve opening by the second valve plate takes place here by pivoting of the valve rod about a pivot axis lying at right angles to the valve rod, with a linear displacement of the valve rod also being mentioned in US 2011/0095218 A1.
US 2015/0014556 A1 reveals a further vacuum valve which has first and second closure elements for the alternative closing of first and second valve openings. The longitudinal stroke and the transverse stroke take place here by a common drive. Starting from the open state of the vacuum valve, this drive adjusts a yoke in the longitudinal adjustment direction, wherein the yoke is guided displaceably in the longitudinal adjustment direction via guide cams which engage in cam recesses. The yoke interacts via a spring with a transmission piece attached to the valve rod. At the end of an adjustment travel of the transmission piece in the longitudinal adjustment direction, said transmission piece runs up against a stop and the yoke is moved further in the longitudinal adjustment direction. Guide cams which engage in cam recesses, which have a curved profile, on the yoke are arranged on the transmission piece. As a result, during the further adjustment of the yoke in the longitudinal adjustment direction, the transmission piece is first of all moved in a transverse adjustment direction until the first closure element closes the first valve opening, and, during the further movement of the yoke in the longitudinal adjustment direction, is moved counter to the transverse adjustment direction until the second closure element closes the second valve opening. Depending on at which point the adjustment of the yoke in the longitudinal adjustment direction is ended, either the first or the second valve opening can therefore be closed. However, it would be desirable for a closure of the second valve opening also to be possible without previously moving the first closure element against the first valve seat.